Evidence For A Radio-Like Mechanism In The Brain Found At The Weizmann Institute

October 13, 1997

REHOVOT, Israel, October 14, 1997...Research conducted at the Weizmann Institute of Science may give a whole new meaning to the phrase "stay tuned." Institute scientists have found evidence that when the brain interprets sensory input, it uses a mechanism remarkably similar to that of an FM radio.

In a study reported in the October 14, 1997, issue of the Proceedings of the National Academy of Sciences (PNAS), the researchers describe how the brain uses this radio-like mechanism to "tune in" to a particular frequency, allowing information gathered through touch to be translated into data about external objects.

This research provides a possible new explanation for the way the brain processes sensory information.

"We hope that our study will contribute to the deciphering of the neural code, the way in which information is encoded by the sensory organs and decoded by the brain," says research team leader Dr. Ehud Ahissar of the Weizmann Institute's Neurobiology Department. He conducted the study with departmental colleague Dr. Sebastian Haidarliu and Dr. Miriam Zacksenhouse of the Technion-Israel Institute of Technology.

"Cracking" the neural code would immensely advance brain research, just as the discovery of the genetic code revolutionized genetics and molecular biology.

Like an FM receiver

When we touch an object, the nerve endings in our skin send electric neural signals to the brain. Until now, scientists studying touch -- or, for that matter, other senses -- have focused on identifying the brain cells that receive these signals and on assessing the signals' intensity.

However, according to Weizmann Institute researchers, this is not the whole story of how the brain actually knows what it's being told by the senses. In the new study, they argue that the timing of the signals also plays a crucial role in this process.

"We found that certain circuits in the brain work on the same principle as an FM radio," says Dr. Ahissar.

In frequency modulation (FM) receivers, the radio is tuned to a particular frequency, or station. During the broadcast this frequency is being constantly altered, or modulated, and the receiver translates these modulations into different sounds.

Similarly, the brain appears to be tuned to its own "radio stations." In the past decade, scientists discovered that the sensory cortical areas of the brain contain cells that oscillate at regular frequencies due to intrinsic mechanisms that do not rely on external stimuli. In their study in PNAS, Ahissar and colleagues show that neural signals generated by touch modulate the oscillation frequency of these cells.

Because the cortex oscillations are regular and persistent, they provide the brain with a "yardstick" against which the timing of incoming signals can be compared. The comparison probably takes place in the thalamus, which receives input both from the cortical areas containing the oscillating cells and from the external sensory stimuli.

It is this comparison that allows the brain to track the timing, or frequency, of the incoming signals, enabling it to decode the information about the object being touched.

Imagine, for example, that you rub your finger against a ribbed surface, such as corduroy fabric. Nerve endings in the skin would send a signal to the brain every time they hit upon one of the fabric's ridges. The thinner and closer-spaced the ridges, the more frequent the signals would be. Thus, the frequency of the signals encodes sensory information about the surface.

In fact, this may be the reason we need to move the finger over a surface in order to better assess its texture: movement allows us to assess the distribution of sensory input over time and better define the object being touched. "The timing of the sensory signals appears to be an inherent part of the neural code," says Ahissar. "In fact, this timing contains so much information about the external world that it would be surprising if the brain made no use of it."

Clarifying the mechanism

The researchers conducted their study on rats, that twitch their whiskers when scouring for food. The rats' brains translate the input from their whiskers into data about the location of objects. The whiskers twitch rapidly, at a rate of about eight motions per second. These motions "notify" the oscillating neurons in the cortex to tune in to a "transmission frequency" of about 8 Hz. When the whiskers hit upon an object, they trigger additional neural signals to the brain, which perturb, or modulate, the regular 8 Hz transmission. The timing of these perturbations is determined by the object's location. Therefore, it allows the brain to create an internal representation of the object's whereabouts. "The brains of primates contain similar oscillating cells, which are tuned to the characteristic frequencies generated when the fingertips rub against an external object," says Ahissar. "Thus, the human brain could use similar FM-radio-like mechanisms to process information obtained through touch and perhaps through other senses as well."

In an extension of this research, Weizmann scientists are currently seeking to demonstrate that the same principle applies when the brain decodes information perceived through other senses, particularly vision.

This research was funded in part by the Minna-James-Heineman Foundation, Germany; the Israel Science Foundation; and the United States-Israel Binational Science Foundation, Israel.

The Weizmann Institute of Science, in Rehovot, Israel, is one of the world's foremost centers of scientific research and graduate study. Its 2,500 scientists, students, technicians, and engineers pursue basic research in the quest for knowledge and the enhancement of the human condition. New ways of fighting disease and hunger, protecting the environment, and harnessing alternative sources of energy are high priorities.

Weizmann Institute news releases are posted on the World Wide Web at http://www.weizmann.ac.il and also at http://www.eurekalert.org

American Committee for the Weizmann Institute of Science

Related Brain Articles from Brightsurf:

Glioblastoma nanomedicine crosses into brain in mice, eradicates recurring brain cancer
A new synthetic protein nanoparticle capable of slipping past the nearly impermeable blood-brain barrier in mice could deliver cancer-killing drugs directly to malignant brain tumors, new research from the University of Michigan shows.

Children with asymptomatic brain bleeds as newborns show normal brain development at age 2
A study by UNC researchers finds that neurodevelopmental scores and gray matter volumes at age two years did not differ between children who had MRI-confirmed asymptomatic subdural hemorrhages when they were neonates, compared to children with no history of subdural hemorrhage.

New model of human brain 'conversations' could inform research on brain disease, cognition
A team of Indiana University neuroscientists has built a new model of human brain networks that sheds light on how the brain functions.

Human brain size gene triggers bigger brain in monkeys
Dresden and Japanese researchers show that a human-specific gene causes a larger neocortex in the common marmoset, a non-human primate.

Unique insight into development of the human brain: Model of the early embryonic brain
Stem cell researchers from the University of Copenhagen have designed a model of an early embryonic brain.

An optical brain-to-brain interface supports information exchange for locomotion control
Chinese researchers established an optical BtBI that supports rapid information transmission for precise locomotion control, thus providing a proof-of-principle demonstration of fast BtBI for real-time behavioral control.

Transplanting human nerve cells into a mouse brain reveals how they wire into brain circuits
A team of researchers led by Pierre Vanderhaeghen and Vincent Bonin (VIB-KU Leuven, Université libre de Bruxelles and NERF) showed how human nerve cells can develop at their own pace, and form highly precise connections with the surrounding mouse brain cells.

Brain scans reveal how the human brain compensates when one hemisphere is removed
Researchers studying six adults who had one of their brain hemispheres removed during childhood to reduce epileptic seizures found that the remaining half of the brain formed unusually strong connections between different functional brain networks, which potentially help the body to function as if the brain were intact.

Alcohol byproduct contributes to brain chemistry changes in specific brain regions
Study of mouse models provides clear implications for new targets to treat alcohol use disorder and fetal alcohol syndrome.

Scientists predict the areas of the brain to stimulate transitions between different brain states
Using a computer model of the brain, Gustavo Deco, director of the Center for Brain and Cognition, and Josephine Cruzat, a member of his team, together with a group of international collaborators, have developed an innovative method published in Proceedings of the National Academy of Sciences on Sept.

Read More: Brain News and Brain Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.